Inetetamab Plus Chemotherapy ± PD-1/PD-L1 in HER2+ Advanced Biliary Cancer

Inclusion Criteria:

* Males or females aged ≥18 years;
* Histologically confirmed HER2-positive metastatic biliary tract cancer;
* ECOG performance status of 0 to 1;
* No prior treatment with anti-HER2 therapies;
* Patients have not received any systemic anticancer treatment in the recurrent/metastatic setting;
* Patients who have experienced disease recurrence more than 6 months after curative surgery; if adjuvant therapy (chemotherapy and/or radiotherapy) was received post-surgery, patients must have had recurrence more than 6 months after completion of adjuvant therapy;
* Presence of at least one measurable lesion;
* Adequate function of major organs as defined by the following criteria;
* Estimated survival of ≥3 months;
* Voluntary participation in this study, signing of the informed consent form, good compliance, and willingness to cooperate with follow-up.

Exclusion Criteria:

* Known allergy or contraindication to any component of the study drugs;
* Previous treatment with anti-HER2 therapies;
* Prior use of immunotherapy;
* Use of immunosuppressive agents within 14 days before the first dose, except:

Intranasal, inhaled, topical steroids, or local injections (e.g., intra-articular) Systemic corticosteroids ≤10 mg/day prednisone or equivalent Steroids for hypersensitivity reactions (e.g., premedication for CT scans)

* Known active central nervous system metastases or carcinomatous meningitis;
* Other malignancies within 5 years, excluding cured cervical carcinoma in situ, basal cell carcinoma, or squamous cell skin cancer;
* Major surgery or significant trauma within 4 weeks before randomization, or planned major surgery;
* Severe cardiac disease;
* Resting dyspnea due to tumor progression or comorbidities, or requiring supplemental oxygen;
* Neuropathy ≥ Grade I per NCI criteria;
* Active interstitial lung disease (ILD) or pulmonary disease requiring bronchodilators;
* History of immunodeficiency;
* Participation in another drug trial within 4 weeks before screening;
* Pregnant or breastfeeding women, or women of childbearing potential with a positive pregnancy test at screening; unwillingness to use effective contraception during and for 6 months after the study;
* Any serious concomitant illness or conditions that may interfere with the planned therapy or render participation unsuitable.